Value Type and Reference Types

Value Type

A data type is a value type if it holds the data within its own memory allocation. Value types include the following:

All numeric data types

Boolean, Char, and Date

All structures, even if their members are reference types

Enumerations, since their underlying type is always SByte, Short, Integer, Long, Byte, UShort, UInteger, or ULong

Every structure is a value type, even if it contains reference type members. For this reason, value types such as Char and Integer are implemented by .NET Framework structures.

You can declare a value type by using the reserved keyword, for example, Decimal. You can also use the New keyword to initialize a value type. This is especially useful if the type has a constructor that takes parameters. An example of this is the Decimal(Int32, Int32, Int32, Boolean, Byte) constructor, which builds a new Decimal value from the supplied parts.

Reference Types

A reference type contains a pointer to another memory location that holds the data. Reference types include the following:

String

All arrays, even if their elements are value types

Class types, such as Form

Delegates

A class is a reference type. For this reason, reference types such as Object and String are supported by .NET Framework classes. Note that every array is a reference type, even if its members are value types.